code: def test_empty_graph(self):
      g = SGraph()
      self.assertEqual(g.summary(), {"num_vertices": 0, "num_edges": 0})
      self.assertEqual(len(g.get_fields()), 3)
      self.assertTrue(g.get_vertices(format="sframe").shape, (0, 1))
      self.assertTrue(g.get_edges(format="sframe").shape, (0, 2))
      self.assertTrue(g.vertices.shape, (0, 1))
      self.assertTrue(g.edges.shape, (0, 2))
      self.assertTrue(len(g.get_vertices(format="list")) == 0)
      self.assertTrue(len(g.get_edges(format="list")) == 0)
  
imports: from __future__ import print_function
  from __future__ import division
  from __future__ import absolute_import
  from ..data_structures.sgraph import SGraph, Vertex, Edge, load_sgraph
  from ..data_structures.sframe import SFrame
  from .None import util
  import pandas
  from pandas.util.testing import assert_frame_equal
  import numpy
  import unittest
  import tempfile
  import json
  import os
  import sys
  import pytest
label_desc: Use image node_id 2 for calling the GraphTests obj's underlying member method code with example usage: obj.test_empty_graph() without return types